I really don't know what to think about this unit...It is nothing like there other DACs costing 10x as much. Can't believe it would do nearly as well. It does not even seem to have any other outputs other than that single headphone out.

I got an HA-02 to amp my W5000s and I hear a very clear "hum" even when the pot is at position zero. I heard the "hum" with all tube amplifiers that I have tested but, after reading the spectacular reviews and synergies between this amplifier and the audio technicas, I hoped that the "hum" would not be noticeable.

Can anybody help me trying to find out if the "hum" is normal, if there is a way to try to mitigate it, etc.? In case it can help: I hear no "hum" at all with solid state amplifiers and I have a decent electrical installation and cables.

The Yamamoto's power supply was replaced with a 220V one by the person that owned it 2 levels before me.

The amplifier is connected to a decent power bar from audioconnexion.de shared with my DAC (Matrix Quattro DAC). Nothing else is connected to the power bar and the power bar is directly connected to the wall socket. All other gear is connected to another power bar that goes to another wall socket located at 2 or 3 meters from the first wall socket.

No, the "hum" issue has been there all the time but I concluded (not proved) that the problem was caused by an external source that I could not find and I finally bought a very nice solid state amp to forget about hums forever. I got to that conclusion after the amplifier was tested by other users that reported no hum and I got a very nice Icon Audio HP8 MK2 SE amplifier (that I returned it) that was also "humming" in my system but not in others.

As much as I love the Yammy with my LCD2s, I have to say that it sounds terrible when driving the Bayer T1s. My Alo Continental V2 sounded far far better. Not sure if the Yammy hates 600ohm cans or if it just dislikes the T1s. Anyone else had a similar experience?

I purchased an unused HA02 amp recently and it turned out that one of the original WE tubes is faulty (starts humming after about 30-45min of use). I got some NOS Philips JAN 408a (a readily available replacement here in the UK) to see whether the problem was tube-related and while I got rid of the noise issue, the Philips tubes have also altered the amp's sound. The the overall warmth and synergy I was getting with the original WE tubes and my ATH W5000 cans is now, unfortunately, gone; Philips tubes are brighter and have more bite. I know HA02 was designed with WE 408a tubes in mind and I would definitely like to retain the amp's original sonic character.

Can anyone suggest a good and reasonably priced source of WE 408A D getter tubes in Europe or UK (apart from ebay)? There are plenty of companies on the other side of the pond but the shipping costs often double the price.